What is the correct size of catheter used for suctioning an 8 mm ET tube?

When determining the appropriate size of a catheter for suctioning an endotracheal (ET) tube, it is essential to consider the inner diameter of the tube. An 8 mm ET tube has an internal diameter of approximately 8 mm, which translates to about 2.5 Fr (French) per mm. Therefore, a catheter approximately three-quarters the size of the inner diameter is commonly used for effective suctioning while minimizing trauma and ensuring airflow.

For an 8 mm ET tube, a 12 Fr catheter is appropriate because it fits within the sizing recommendation of being less than or equal to half of the ET tube's internal diameter. This size allows for adequate lumen availability for suctioning secretions without completely occluding the airflow.

Using a catheter size that is too small would compromise the effectiveness of suctioning, while a size that is too large could lead to injury to the airway, discomfort for the patient, and potential complications. Hence, a 12 Fr catheter is the correct choice for suctioning an 8 mm ET tube to effectively clear secretions while ensuring patient safety and comfort.